Telephone selector switch with common drive for vertical and rotary wiper motion



w. LOHS 2,844,656 TELEPHONE SELECTOR SWITCH WITH COMMON DRIVE July 22, 1958 FOR VERTICAL AND ROTARY WIPER MOTION 3 Sheets-Sheet 1 Filed May 16 1955 July 22, 1958 w. LOHS 2,844,656

TELEPHONE SELECTOR SWITCH WITH COMMON DRIVE FOR VERTICAL AND ROTARY WIPER MOTION Filed May 16, 1955 3 Sheets-Sheet 2 fluemjorr 20/35.

July 22, 1958 w. LOHS 2,8

TELEPHONE SELECTOR SWITCH WITH COMMON DRIVE FOR VERTICAL AND ROTARY WIPER MOTION Filed May 16, 1955 3 Sheets-Sheet 3 United St. tes Patent TELEPHONE SELECTOR SWITCH WITH COMMON DRIVE FOR VERTICAL AND ROTARY WIPER MOTION Willy Lohs, Munich, Germany, assignor to Siemens & Halske Aktiengesellschaft, Munich and lrcrlln, Germany, a corporation of Germany Application May 16, 1955, Serial No. 508,592 In Germany September 30, 1949 Public Law 619, August 23, 1954 Patent expires September 30, 1969 Claims. (Cl. 179-27.52)

The present invention relates to vertical and rotary or two-motion selector switches for telecommunication installations and particularly for telephone or teletypewriter systems or the like which carries out two setting motions in planes perpendicular to each other and has a drive motor assigned jointly to the two directions of motion.

Previously known two-motion selectors comprising a common stepping motor for the two directions of motion, for example, as described in German Patents Nos. 678,077 and 690,052, require mechanical clutches which are actuated' by an electromagnet and which effect the shifting from one direction of motion to the other. The electrically controlled clutches cause additional expense, and such clutches produce noises and are subject to extensive wear.

The invention provides a clutchless two-motion selector with common drive for both directions of motion which combines the advantages peculiar to the three customary types of selectors, namely, two-motion selectors, powerdriven selectors and crossbar selectors. Each of these three known types of selectors which are in wide use has characteristic advantages and also disadvantages stemming from its structural peculiarities.

The two-motion selectors have the advantage over the power-driven selectors of an advantageous setting motion of the wipers (rectangular motion) which makes it possible to reach the desired bank contacts on a short path, that is, with a maximum of 20 setting steps for 100 contacts. This motion, however, is generally effected by two separate magnet step-by-step switches which cause strong vibrations and hum and contact noises and which limit the setting speed to at most 35 steps per second. The customary two-motion selector has only one frictional contact lying in the talking circuit, since the current feed to the wiper can be effected, due to the returning rectangular motion, over a flexible line cord, but the line cord becomes susceptible to breakdown after long use, and imperfect friction contacts are frequently the cause of undesirable noises in carrying on conversation over the resulting connections. By the use of silver contacts, the aforementioned disadvantages could be in part remedied. The previously known two-motion selectors with contact pressure on the bank contacts, however, require a special lifting magnet so that the wipers, during their movement relative to the bank contacts, are out of engagement therewith, the engagement being elfected after completion of the selecting operation.

The power-driven selector has the advantage of being driven by a rapid, noiseless, vibration-free selector motor. The great stepping speed acts however only in part upon the speed of the setting operation, since the hundredth bank contact is reached over the successively arranged bank contacts after the wipers have been rotated one hundred steps. The long sliding path produces considerable wear of thecorresponding parts. The rotating,

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nonreturning motion of the wipers makes it necessary to provide a second friction contact for the current feed in the talking path in series with the involved bank contacts. The use of wipers provided with silver contact points is as such possible but requires a special lifting magnet.

The crossbar selector has the advantage that contact is made by precious metal contacts which are actuated in the manner of relay contacts. This advantage, however, is obtained in the case of a one hundred point selector at the expense of 20 magnet systems and correspondingly large space requirements, Without it being possible to utilize the possibility of multiple seizure afforded by directly operating selector systems.

Summarizing, it may be said that coordinate motion appears to be the best solution for a directly operating selector; a selector motor appears to be the best solution for the drive; and precious metal pressure contact appears to be the best solution for effecting contact operation.

The present invention now makes it possible to provide for a cooperation of parts resulting in the advantages of the three mentioned types of selectors. The selector switch in accordance with the invention is characterized by completely vibrationless operation and extremely simple construction.

These advantages are in accordance with the present invention realized by actuating a longitudinally and rotatably displaceable wiper carrier, which is arranged on the switch shaft, by means of a screw drive rotated in the same direction by .a stepping motor, the axially displaceable member of the screw drive having a disengageable guide and being restored by the action of a restoring force, for example, a weight or spring.

In accordance with a further object and feature of the invention, the wiper carrier, which is provided with the wipers serving for pressure engagement with bank contacts, comprises a shaped part of such form that, to gether with a second shaped part moved by a magnet, it forms a disengageable linear guiding and a guide during the rotation of the wipers.

The use of a screw drive in combination with a disengageable linear guide makes the desired vertical and rotary (coordinate motion) of the wipers possible without the use of a coupling by a stepping motor, of the type customary in connection with power-driven selectors, which rotates in the same direction and permits the return of the wipers into the starting position without reversal means since the wipers after leaving the bank contacts are turned further under the influence of the restoring force by the screw drive in the same direction as in the setting motion so that the wipers reach their initial position after one complete revolution. The closed cycle rotation of the wipers makes it possible to construct the switch so that the wipers are operated in pressure contact engagement with bank contacts.

The screw drive may be constructed in various manner as shown in the embodiments described below with reference to the accompanying diagrammatic drawings showing only those parts necessary for an understanding of the invention.

Fig. 1 is a diagrammatic perspective view of a selector switch, of which, for the sake of simplicity, only one wiper and one row of bank contacts are shown;

Figs. 2 to 4 are different embodiments of the screw drive; and

Fig. 5 is a diagrammatic perspective view of a selector switch in which a wiper is brought into engagement with bank contacts only in its operating position.

As can be seen from Fig. 1, the wiper 5 carried by a tubular wiper carrier 3, serving the bank contacts 4, is movable longitudinally and rotationally on the shaft 2 fastened in selector frame 1. Only one row of bank contacts for coaction with the pressure contact wiper is shown, other wipers and corresponding contact banks having been omitted. The displacement of the wiper carrier 3 against the action of the restoring spring 6 is effected by a motor drive (not shown) through the medium of a pinion 7 which rotates the selector drive gear 8 in the direction indicated by the arrow P1. A motor for this purpose is disclosed in U. S. Patent No. 1,978,700. In order to convert the rotary motion of the gear 8 into the vertical and rotary motion of the wiper carrier 3, there is provided the screw drive 9, 10.

As will be presently explained with reference to Figs. 2 to 4, the screw drive may be constructed in various manner. As is well known, a screw drive comprises two parts, namely, a screw bolt and a screw nut. If the screw bolt is stationary, the nut upon its rotation moves axially thereof, and conversely, if the nut is stationary, the screw bolt upon rotation moves in axial direction. If the screw bolt is during its rotation prevented from moving longitudinally and the nut is freely movable, the latter will turn with the same speed as the screw bolt. If the nut is held against turning by a stop, it will necessarily move axially on the rotating screw bolt. Upon appreciating the relative movements between a screw and a nut, the manner of operation of the screw drive for the desired purpose of converting the rotary motion of the driving gear into the vertical and rotary motion of the wiper carrier will be readily understood.

In the structure shown in Fig. 1, the nut thread is formed in part 9 of the driving gear 8 which is rotatable about the shaft 2, and cannot move axially. The screw bolt thread 10 is cut into a part carried by the wiper carrier 3 so that upon rotation of the nut part 9, the screw bolt 10, that is, the wiper carrier, is carried along by friction and rotates with the angular velocity of the driving gear 8. As soon, however, as the rotation of the wiper carrier 3 is impeded, the latter must necessarily move axially in the direction indicated by the arrow P2. In order to effect the desired vertical displacement of the wiper carrier 3, the latter is fixedly connected with the bracket member 11, which has a comblike guide element 16. An arcuate guide plate 13 is fastened to the selector frame and the recesses in the guide 16 by the teeth 12 can engage the arcuate plate. The number of recesses in the guide 16 corresponds to the number of vertical steps and the distance between the individual recesses corresponds to the spacing between individual bank contact rows 4. The guide 16 of the bracket 11 serves, in combination with a stop 15, controlled by magnet 14, as linear guide upon the axial displacement of the wiper carrier, which takes place when, upon rotation of the drive gear 8, the guide 16 of the bracket 11 comes against the stop and stops the rotation of the wiper carrier 3. The rotary displacement imparted to the selector drive gear 8 by the selector motor by means of the pinion 7 is therefore first of all converted by the screw drive 9, 10, in combination with guide 16 and stop 15, into a vertical displacement corresponding to a number of vertical steps.

Upon the following switching operation, the rotary displacement imparted to the selector drive gear 8 is utilized to produce the rotary selector steps. In such operation, magnet 14 is initially energized so that the stop 15 is removed from engagement with the guide 16 of the bracket 11. The extension 17 of stop 15 is shaped so that it can pass through the recesses formed by the teeth 12. The arrangement permits operation with a relatively small stroke of the armature of the magnet 14. In order to assure the rotation upon reaching the last vertical step, the recess 18 corresponding to such step is cut deeper so that even when the magnet 14 is denergized, the extension 17 can enter into this recess and the linear guiding becomes ineffective.

The rotation of the wiper carrier takes place as soon as the extension 17 of the stop 15 is disengaged from the guide 16. Due to the swinging of the bracket 11, the arcuate guide member 13, fastened to the selector frame,

ture shown in Fig. 1.

comes into engagement with a recess in the guide 16 and assures the rotation of the wipers in the level reached during the vertical displacement. Depending upon whether the switch is used as a group selector or as a connector, the wipers 5 are stopped on the bank contacts determined respectively by hunting or by dial pulses.

Upon the release of the switch, the drive gear 8 is again rotated by the stepping motor and the rotary motion of the wiper carrier takes place until the wipers have left the bank contacts. The guide means 16 of the bracket 11 disengages the arcuate guide member 13. From this time on, two superimposed motions become effective, one motion being produced by the restoring force of the spring 6 which attempts to move the wiper carrier 3 downwardly, while the other motion is caused by the rotating drive gear.

If one considers the nut thread 9 to be stationary, the screw 10 upon axial downward motion opposite to the direction P2 not only moves axially, but also rotates in the direction P1. Since the nut thread 9 now rotates with the same angular velocity as the driving gear 8 in the direction indicated by the arrow P1, the two rotary motions, which are imparted to the wiper carrier by the driving gear 8 and by the restoring spring 6 are added. For the sake of a clearer understanding, the path of motion of the end of the wiper is shown by dot-dash lines.

The wiper 5 is first of all raised from its initial position a into the dotted-line position b. It then rotates into the position 0. Upon the restoring motion, the wiper moves from 0 up to the end of the bank contacts into position d. The wiper is thereupon lowered to the starting level. By superimposing the axial motion and the two rotary motions, there is produced an oblique path of motion from the point d to the point e. The wiper is thereupon further rotated out of position e by the stepping motor until it has reached the initial position a, in which the guide 16 of the bracket 11 again rests against the extension 17 of the armature 15 and is stopped by a suitable contact of the stepping motor.

As already mentioned, the screw drive for the vertical and rotary motion of the switch may be effected in different manner.

Fig. 2 shows a screw drive corresponding to the struc- The switch shaft is designated 2 and the wiper carrier 3. The nut 9 is fixedly connected with the driving gear 8 and the screw 10 forms a unit with the wiper carrier 3.

In the structure shown in Fig. 3, the wiper carrier 3 is fixedly connected with the nut 9, and the screw 10 is fixedly connected with the driving gear 8.

In the case of the screw drive shown in Fig. 4, two helical gears 19 and 20 are used instead of a nut and a screw, helical gear 19 being fixedly connected with the driving gear 8, and gear 20 being fixedly connected with the wiper carrier 3. It is of course not necessary for the axes of the gears to lie in two intersecting planes as shown in the example of Fig. 4; they may for instance also be arranged in two planes parallel to each other.

In Fig. 5, there is shown a further embodiment of the invention, the magnet 14 for controlling the linear motion serves at the same time to control an actuating and releasing motion of the wipers, so that they move relative to the bank contacts out of engagement therewith and into engagement with selected bank contacts only in their operating positions. For this purpose, the guide bracket 21 of the armature of magnet 14 is moved in a plane oblique to the switch shaft, that is, the direction of motion of the guide comb 21 has a radial component and a component directed along the switch shaft. When the armature is in released position, the segment-shaped part 22 has its end surface resting against the guide surface of the member 21. The segment-shaped projection 22 which is fixedly connected with the wiper carrier 3 in a plane perpendicular to the selector axis has an extension 23 which cannot enter into the recesses of the teeth of come upon sliding in the threadlike groove.

member 21 when the armature of the magnet 14 is in released position. In the same way as in the structure shown in Fig. 1, upon the vertical displacement, the wiper carrier 3 is prevented from effecting rotary motion by the linear guide consisting of the parts 21, 22, 23, so that the rotary motion of the driving gear 8 is converted by the screw drive 9, into the corresponding vertical motion.

The screw drive comprises a threadlike groove 9 cut in a semispherical shell for engagement by a follower extension 10 fixedly connected with the wiper carrier 3, which extension may have the shape of a roller so that only the smallest possible frictional forces need be over- The pitch of the threadlike groove is made about 45. By the energizing of the magnet 14, the rotary motion of the switch is brought about since after the displacement of the guide 21 the extension 23 can enter into the recess which corresponds to the vertical step selected. The segmentshaped member 22 serves to guide the wiper carrier during the rotation. As soon as the wiper 5 is in a position relative to a selected contact, the magnet 14 deenergizes and the downwardly directed component of the motion of the member 21 in a direction opposite to P2 is transmitted to the wiper carrier over the segment-shaped part 22. Since the motion of the wiper carrier is also determined by the screw drive 9, 10, the wiper 5 will be placed in engagement with the bank selected contact in an oblique motion path which is similar to the path de of Fig. 1.

Upon the release of the selector, the magnet 14 is temporarily again energized so that the wipers are raised relative to the bank contacts and disengaged therefrom.

The control of the motions of the switch is effected by means of further wipers which serve to test lines to ascertain Whether they are idle or busy and therefore are in continuous engagement with the corresponding bank contacts during the setting or selecting rotation thereof. These test wipers may form simple friction contact points while the contact points in the line conductors are precious metal pressure contact points.

In view of the release operations described in connection with Fig. 1, a detailed description referring to Fig. 5 is omitted.

In order to ease the motion of the wiper carrier 3 upon its release into the initial position, a bufier spring 24 is provided.

It may be mentioned that the control of the pressure contact and lifting motion of the wipers could be effected in some other manner than that shown in accordance with Fig. 5. For instance, the segment shaped guide plate 22 of the Wiper carrier could be provided on its periphery with teeth, the recesses of which correspond to the thickness of the guide member 21. This would have the effoot that after the swinging in of the guide member 22, the comb of part 21 actuated by magnet 14, again comes in front of a tooth of the guide segment 22 so that upon the next rotary step of the driving gear 8, another longitudinal displacement of the Wiper carrier 3 and thus a pressure engagement of the selected bank contacts 4 is effected. The comb 21 in such case however must be so constructed that it permits a small longitudinal motion of the segment 22. This can be most simply obtained if the dimensions of the recesses and of the teeth are suitably adapted to each other.

Changes may be made within the scope and spirit of the appended claims.

I claim:

1. A selector switch comprising bank contacts, wipers for selective engagement with said bank contacts, a carrier for said wipers, a common drive device for imparting to said carrier and therewith to said wipers vertical and rotary motions, respectively, to move said wipers selectively into engagement with said bank contacts, said drive device comprising a first screw-threaded vertically and rotatably movable element connected with said wiper carrier and a second solely rotatable screw-threaded element geared to said first element, a driving member fixedly connected with said second element, means for rotating said driving member to rotate said second element to impart rotation to said first element in identical direction during the setting operation of said wipers and during the release thereof, and guide means for said first vertically and rotatably movable element comprising two members, a first one of said guide members being fixedly connected with said Wiper carrier, and a magnet for controlling a second one of said guide members, said guide members cooperating to hold said first element against rotation for the purpose of converting torque placed thereon by said second element into vertical motion of said wiper carrier and the wipers carried thereby.

2. A selector according to claim 1, comprising a toothed gear wheel constituting said driving member.

3. A selector according to claim 1, wherein said guide members cooperate as linear guide means for the vertical motion of said wiper carrier and as a rotation guide means during the rotation thereof.

4. A selector according to claim 3, wherein said first guide member is a member projecting radially of said Wiper carrier and forming a toothed portion extending axially of said wiper carrier, the recesses formed by the teeth of said guide member corresponding to vertical steps, said second guide member being fixedly mounted for entering one of said recesses incident to the rotation of said wipper carrier in a level to which it had been moved, a stop member, and a magnet for operating said stop member, said stop member engaging the side of said toothed guide member as a guide during the vertical motion of said wiper carrier.

5. A selector according to claim 4, said magnet being operative to retract said stop member from engagement with said side of said guide member.

6. A selector according to claim 5, wherein the recess in said toothed portion corresponding to the top level to which said wiper carrier may be operated and said stop, respectively, are formed so as to inactivate the vertical guide function thereof for the purpose of permitting rotation of said wiper carrier.

7. A selector according to claim 3, comprising a flat segment-shaped member secured to said wiper carrier and extending perpendicularly to the switch axis, and a magnet operated coacting member forming comblike teeth.

8. A selector according to claim 7, wherein said coacting member extends radially of the switch axis for coaction with a segment-shaped member secured to said wiper carrier and extending in a direction perpendicular to the switch axis, one edge of said segment-shaped member cooperating as a vertical guide with said coacting member and the segment portion thereof cooperating therewith as a rotary guide responsive to displacement thereof by said magnet.

9. A selector according to claim 8, comprising means for causing disengaging displacement of Wipers relative to bank contacts, said magnet controlling the operation of said means.

10. A selector according to claim 8, wherein the displacement of said member forming comblike teeth, by said magnet, extends in a plane oblique to the switch axis, the recesses formed in said member to form said teeth extending in parallel to the plane of said segment-shaped member, the release of said magnet causing axial shifting of said wiper carrier for the purpose of controlling the pressure contact operation of said wipers relative to the associated bank contacts.

No references cited. 

